• ETRI Journal
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• v.33 no.5
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• pp.679-688
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• 2011

A new discrete-amplitude pulse width modulation (DAPWM) scheme for a high-efficiency linear power amplifier is proposed. A radio frequency (RF) input signal is divided into an envelope and a phase modulated carrier. The low-frequency envelope is modulated so that it can be represented by a pulse whose area is proportional to its amplitude. The modulated pulse has at least two different pulse amplitude levels in order that the duty ratios of the pulse are kept large for small input. Then, an RF pulse train is generated by mixing the modulated envelope with the phase modulated carrier. The RF pulse train is amplified by a switching-mode power amplifier, and the original RF input signal is restored by a band pass filter. Because duty ratios of the RF pulse train are kept large in spite of a small input envelope, the DAPWM technique can reduce loss from harmonic components. Furthermore, it reduces filtering efforts required to suppress harmonic components. Simulations show that the overall efficiency of the pulsed power amplifier with DAPWM is about 60.3% for a mobile WiMax signal. This is approximately a 73% increase compared to a pulsed power amplifier with PWM.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1480-1489
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• 2017

In this study, a carrier-based pulse-width modulation (PWM) method for two-level voltage source inverters in the over-modulation region is proposed. Based on the superposition principle, the reference voltage vectors outside the linear modulation boundary are adjusted to relocate to the vector hexagon, while their fundamental magnitudes are retained. In accordance with the adjusted reference vector, the corresponding modulated waves are respectively deduced in over-modulation mode I and II to generate the gate signals of the power switches, guaranteeing the linearity of the fundamental output phase voltage in the over-modulation region. Moreover, due to the linear relationship between the voltage vector and the duty ratios, the complicated sector identification and holding angle calculation found in previous methods are avoided in the modulated wave synthesis, which provides great simplicity for the proposed carrier-based over-modulation strategy. Experimental results demonstrate the effectiveness and validity of the proposed method.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.1
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• pp.92-97
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• 2005

This paper discusses an intelligent digital redesign technique for designing a fuzzy pulse-width-modulated (PWM) control. First when we are given a well-designed fuzzy analog control, the equivalent digital control is intelligently redesigned. Using the similar technique we intelligently redesign the fuzzy PWM control from the intelligently redesigned fuzzy digital control. A stabilizability of the intelligently redesigned PWM control is rigorously analyzed.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.179-185
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• 2005

This paper presents a novel circuit topology of a high efficiency single-phase power conditioner. This power conditioner is composed of time-sharing sinewave absolute pulse width modulated boost chopper with a bypass diode in the first power processing stage and time-sharing sinewave pulse width modulated full-bridge inverter in the second power processing stage operated by time-sharing dual mode pulse pattern control scheme. The unique operating principle of the two power processing stage with time-sharing dual mode sinewave modulation scheme is described with a design example. This paper proposes also a sinewave tracking voltage controlled soft switching PWM boost chopper with a passive auxiliary edge-resonant snubber. The new conceptual operating principle of this novel power conditioner related to new energy utilization system is presented and discussed through the experimental results.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.335-339
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• 2001

The recent advancements in power electronic switching devices have enabled high frequency switching operation and have improved the performance of pulse-width modulated (PWM) inverters for driving induction motors. But, the insulation failures of stator winding have attracted much concern due to high dv/dt of IGBT PWM inverter. In this paper, the test results for evaluation on the stator winding insulation of low-voltage induction motors for IGBT PWM inverter applications are presented. The insulation characteristics are analyzed with partial discharge and dissipation factor tests. Also, insulation breakdown tests by switching pulse voltage are performed. An effective insulation technique to enhance the insulation strength is suggested from the test results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.672-675
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• 2010

Spray characteristics for the modulation with a pulsed spray in low-frequency region were investigted by performing with additional internal pulsed injection. The 1st perturbative flow was generated by rotating-type pulsed device and the 2nd pulse source generated by the magnetic valve was used to modulate the 1st flow. A pattern of the modulated spray was observed through FFT result and visualization. In case of modulated spray with the 2nd pulse control, the width of up and down motion of the modulated spray is smaller than that of the spray without the 2nd pulse. Also, the depth of penetration of the down stream is higher than that of spray without the 2nd pulse.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.113-122
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• 2011

This paper introduces and develops an efficient method for measuring power factor (PF) and its nature under nonlinear load current situations. The method is based on generating a pulse width modulated signal whose width correlates to the value of PF. This signal can then be employed as a feedback signal for controlling PF related power quantities in a system. This method has the advantages of its simple implementation, less computational complexity, and its allowable error of less than 4[%], which is justified by the computer simulation results.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.25-28
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• 2002

In this paper, 2 phase modulated SRPP-PWM(Separately Random Pulse Position PWM) is proposed. This PWM technique is based on the 2 phase modulated SVPWM(Space Vector Pulse Width Modulation). In according to the theory of SVPWM, 2 phase modulated SVPWM uses two pulses, not three pulses as in 3 phase modulated SVPWM. In the proposed SRPP-PWM scheme, each of two phase pulses is located randomly in each switching interval. The experimental results show that the voltage and switching noise harmonics are spread to a wide band area. Also, the performance of the proposed 2 phase modulated SRPP-PWM and the conventional SVPWM are compared to each other In result, the speed response is nearly similar to each other from the viewpoint of the v/f constant control.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.10a
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• pp.443-446
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• 2004

This paper discusses an intelligent digital redesign technique for designing a fuzzy pulse-width-modulated (PWM) control. First when we are given a well-designed fuzzy analog control, the equivalent digital control is intelligently redesigned. Using the similar technique we intelligently redesign the fuzzy PWM control from the intelligently redesigned fuzzy digital control. A stabilizability of the intelligently redesigned PWM control is rigorously analyzed.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.14-20
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• 1997

Due to several advantages of Pulse Width Modulated(PWM) Converter, such as unity power factor with low-harmonics and energy regeneration, PWM converter has been widely used in industrial application. In every application of energy conversion equipment, the design and implementation must be carried out considering performance and cost. High quality with low cost is the best choice for energy conversion equipment. High dc link voltage can reduce inverter and motor side losses and system dimension compare to low dc link voltage. Analog controller can make PWM converter cheaper without considerable degradation of the performance than digital controller. This paper shows the simplified analog controller-for 600V dc link voltage using stationary reference frame control and the simulation results.